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I bought a couple of "STFT-9004":
http://www.njrc.jp/product/pdf/densi/STFT.pdf
a while back pretty cheap (around USD$3.25) as a surplus item thinking I could do something with them some time in the future. (Also, someone on another bbs measured the freq. response, and reported that they were not too bad despite being telecom transformers.) So, tried one just as 600:1200 (input transformer hookup) which gives:
sqrt(1 200 / 600) = 1.41421356
which is not much "free gain" since the step-up ratio is not high. (I terminated the secondary with 1.2k? R.) Sounded fine (didn't seem to have any peaking or weirdness) as far as I could tell, but didn't seem to have any particular point due to not really giving noticable increase in signal(and S/N).
Recently, I stumbled on this (Jensen app. note) :
http://www.jensen-transformers.com/as/as047.pdf
and I thought, "Hey, maybe I could do something like that with the cheapo transformers!"(thought balloon).
So, tried a little experiment, hooking up two as shown in the application note with a 300 ohm fixed R terminating the primary, and measuring across the series connected secondaries with my LCR meter (1kHz, 10kHz). At 1kHz, I got 2.574k ohms, and at 10kHz, 2.643k ohms. This seemed to say the secondary was about 2.6k( and pri. was 300ohms--I think as humbucking hookup as shown in the app.note), and sqrt(2600/300)=2.94, so ratio 1:2.94. This was looking good to get a hotter signal(from my SM58). (Finally
) my question/s. Is there anything wrong with the way I'm seeing this, or anything to watch out for using two transformers this way?
http://www.njrc.jp/product/pdf/densi/STFT.pdf
a while back pretty cheap (around USD$3.25) as a surplus item thinking I could do something with them some time in the future. (Also, someone on another bbs measured the freq. response, and reported that they were not too bad despite being telecom transformers.) So, tried one just as 600:1200 (input transformer hookup) which gives:
sqrt(1 200 / 600) = 1.41421356
which is not much "free gain" since the step-up ratio is not high. (I terminated the secondary with 1.2k? R.) Sounded fine (didn't seem to have any peaking or weirdness) as far as I could tell, but didn't seem to have any particular point due to not really giving noticable increase in signal(and S/N).
Recently, I stumbled on this (Jensen app. note) :
http://www.jensen-transformers.com/as/as047.pdf
and I thought, "Hey, maybe I could do something like that with the cheapo transformers!"(thought balloon).
So, tried a little experiment, hooking up two as shown in the application note with a 300 ohm fixed R terminating the primary, and measuring across the series connected secondaries with my LCR meter (1kHz, 10kHz). At 1kHz, I got 2.574k ohms, and at 10kHz, 2.643k ohms. This seemed to say the secondary was about 2.6k( and pri. was 300ohms--I think as humbucking hookup as shown in the app.note), and sqrt(2600/300)=2.94, so ratio 1:2.94. This was looking good to get a hotter signal(from my SM58). (Finally
) my question/s. Is there anything wrong with the way I'm seeing this, or anything to watch out for using two transformers this way?